A new family and genus in Dothideales for Aureobasidium-like species isolated from house dust

An international survey of house dust collected from eleven countries using a modified dilution-to-extinction method yielded 7904 isolates. Of these, six strains morphologically resembled the asexual morphs of <i>Aureobasidium</i> and <i>Hormonema</i> (sexual morphs ?<i>Sydowia),</i> but were phylogenetically distinct<i>.</i> A 28S rDNA phylogeny resolved strains as a distinct clade in <i>Dothideales</i> with families <i>Aureobasidiaceae</i> and <i>Dothideaceae</i> their closest relatives. Further analyses based on the ITS rDNA region, β-tubulin, 28S rDNA, and RNA polymerase II second largest subunit confirmed the distinct status of this clade and divided strains among two consistent subclades. As a result, we introduce a new genus and two new species as <i>Zalaria</i><i>alba</i> and <i>Z. obscura</i>, and a new family to accommodate them in <i>Dothideales</i>. <i>Zalaria</i> is a black yeast-like fungus, grows restrictedly and produces conidiogenous cells with holoblastic synchronous or percurrent conidiation. <i>Zalaria</i> microscopically closely resembles <i>Hormonema</i> by having only one to two loci per conidiogenous cell, but species of our new genus generally has more restricted growth. Comparing the two species, <i>Z. obscura</i> grows faster on lower water activity (a_w) media and produces much darker colonies than <i>Z. alba</i> after 7 d. Their sexual states, if extant, are unknown.